QGraphicsScene and QGraphicsVideoItem extreme high CPU use on Mac

[SGaist]

Hi and welcome to devnet,

What version of PyQt5 are you using ?
How did you install it ?
What version of macOS are you running ?
Can you tell what model is you machine ?

[Bouke]

Hi:
PyQt5 5.9.2, installed with Pip in a Python 3.6.8 venv
But just updated to 5.14.2, does not seem to make a difference.

Running OS 10.15.4 on an Imac (Retina, quad core i5, Radeon Pro 555 2 GB)

Does that help?

[SGaist]

I forgot, what video codec has issues ?

[Bouke]

You did not forget, I did not told you :-)
H264 (x264) does play, although suffering from the high CPU consumption.
ProRes flickers (black frames alternating video frames).

The CPU use increases when the window gets bigger.

I suspect there are too many updates or something like that, Qmediaplayer in a 'bare' surrounding does not have these issues.

[SGaist]

Try using a QOpenGLWidget as viewport of your QGraphicsView.

[Bouke]

@SGaist
Well, I would if I could, but I'm new to Python (and not a real coder, I'm coming from Adobe Director...)
Do you have any pointers?
thx,

[SGaist]

Something like:

my_scene.setViewport(new QGLWidget())

[Bouke]

@SGaist
Ok, I've added to my QGraphicsView:

self.widget = glWidget(self)
self.setViewport(self.widget)

class glWidget(QGLWidget):
def init(self, parent=None):
QGLWidget.init(self, parent)

[Bouke]

that was send out too fast... (Can't I edit my own posts?)
CPU use is now reduced to a quarter of what it was before, so that's the good news.
The bad news is that the video is displayed twice too big. (Due to my Retina screen I think...)

[Bouke]

Dirty hack that sorta kinda fixes stuff:

from PyQt5 import QtWidgets, QtGui, QtCore, QtMultimediaWidgets, QtMultimedia
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PyQt5.QtMultimedia import *
from PyQt5.QtMultimediaWidgets import *
import sys


from PyQt5.QtOpenGL import *

VIDEO_WIDTH = 1200
VIDEO_HEIGHT = int(VIDEO_WIDTH / 16 * 9)å

########################################
#
########################################
class MyVideoView(QGraphicsView):
    def __init__(self, parent=None):
        super(QGraphicsView, self).__init__(parent)
        # self._main = parent

        # 9% CPU use, rem out this to get high CPU use (depends on window size, up to 100%)
        self.widget = glWidget()
        self.setViewport(self.widget)


        self.setBackgroundBrush(Qt.black)
        self._scene = QGraphicsScene(self)
        self.setScene(self._scene)
        self._videoItem = QGraphicsVideoItem()
        # self._videoItem.setPos(0, 0)
        self._scene.addItem(self._videoItem)

        self._overlay = QPixmap(VIDEO_WIDTH, VIDEO_HEIGHT)
        self._overlay.fill(QColor(0, 150, 0, 150))
        self._graphicsPixmapItem = self._scene.addPixmap(self._overlay)

        self._player = QMediaPlayer(self)
        self._player.setVideoOutput(self._videoItem)

    def loadVideo(self, fn):
        self._player.setMedia(QMediaContent(QUrl.fromLocalFile(fn)))
        self._player.play()
        # self._player.setPlaybackRate(0.5)

class glWidget(QGLWidget):
    def __init__(self, parent=None):
        QGLWidget.__init__(self, parent)

class Video(QMainWindow):

    def __init__(self, parent=None):
        super(QMainWindow, self).__init__(parent)
        self.setWindowTitle("Video window")
        self._splitter = QSplitter(Qt.Vertical)
        self.setCentralWidget(self._splitter)

        self._videoView = MyVideoView(self)

        self._splitter.addWidget(self._videoView)
        self._videoView.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self._videoView.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.show()
        self._videoView.loadVideo('/Volumes/Data/videofiles/demo_BITC 2.mov')
        self.resizeEvent(False)

    def resizeEvent(self, e):
        # print(dir(QResizeEvent))
        if not e:
            _w = self.geometry().width()
            _h = self.geometry().height()
        else:
            _w = e.size().width()
            _h = e.size().height()


        self._videoView._videoItem.setSize(QSizeF(_w / 2, _h / 2))

        # do not get a feedback loop
        try:
            if self.ignorscaling:
                self.ignorscaling = False
                return
        except:
            pass
        self.ignorscaling = True

        # order of stuff is important here!
        self._videoView._videoItem.setSize(QSizeF(_w, _h))
        _w = self._videoView._videoItem.sceneBoundingRect().right()
        _h = self._videoView._videoItem.sceneBoundingRect().bottom() - self._videoView._videoItem.sceneBoundingRect().top()

        self.resize(_w, _h)


if __name__ == '__main__':
    app = QApplication(sys.argv)
    app.setQuitOnLastWindowClosed(True)
    w = Video()
    sys.exit(app.exec_())